The present invention concerns a new acidic polycyclic ether antibiotic having the formula: ##STR1## wherein in Me=CH.sub.3 and PR=CH.sub.3 CH.sub.2 CH.sub.2, having absolute stereochemistry as shown; pharmaceutically acceptable cationic salts thereof; nutrient feed compositions comprising said antibiotic for poultry, cattle or swine; its use as an anticoccidial agent in poultry, in the treatment or prevention of swine dysentery, or as a growth promotant in cattle or swine; a fermentation method for its preparation; and the Streptomyces sp. microorganism which produces said antibiotic in said fermentation method.
The compound (I), which is a homolog of monensin, is a new member of the acidic polycyclic ether group of antibiotics. This family includes, in addition to monensin (The Merck Index, 10th Ed., Merck and Co., Inc., Rahway, N.J., 1983, monograph no. 6100), such well known agents as nigericin (loc. cit., monograph no. 6390), narasin (loc. cit., monograph no. 6271), lasalocid (loc. cit., monograph no. 5204), and salinomycin (loc. cit., monograph no. 8193). The subject has been reviewed by Westley, "Polyether Antibiotics", Adv. Appl. Microbiol., vol. 22, pp. 177-223 (1977). These compounds are generally known as coccidiostats, as feed additive-growth promotants, and/or as agents useful against swine dysentery.